The present invention refers to a method of and apparatus for cleaning objects of plastics processing machines from plastic coatings or residues adhering to the surface of the objects.
European Patent No. EP-A2-0 343 413 describes a cleaning apparatus with a heat insulated treatment container which is closable in air-tight manner by a lid carrying an activated carbon filter. The container has a treatment chamber which is filled with a liquid heat transfer fluid and receives the objects being cleaned from plastic residues. The heat transfer fluid is heated by a heating unit above the melting temperature of the plastic residues adhering to the surface of the objects. In order to attain an even temperature distribution and for shortening the treatment period, the heat transfer fluid is circulated by an impeller pump which is immersed in the heat transfer fluid. The treatment chamber is divided in a main compartment and a pump compartment, with the axis of the pump compartment extending parallel to the center axis of the main compartment. Upper and lower passageways connect the pump compartment with the main compartment. Inert gas is introduced into the space above the liquid level of the heat transfer fluid to prevent a decomposition of heat transfer fluid.
Objects of plastic processing machines from which adhering plastic residues should be removed include extrusion heads, blow heads, extrusion/blow heads, distributors, nozzles etc., i.e. objects which include bores and/or channels filled at least partly with solidified plastic material. Especially when the objects have long bores and/or bores of complicated structure, treatment periods become relatively long, and a dismantling before cleaning and subsequent re-assembly are required, rendering the overall cleaning process time consuming and complicated.